Generally speaking, the present invention relates to a means for measuring the level of a liquid and more specifically to a capacitive means for measuring the level of a liquid comprising a container wherein said level of said liquid may be measured, at least one cluster of at least two electrodes each of which is situated adjacent to said container, a means electrically coupled to at least one of said electrodes of said cluster for supplying an electrical signal thereto, and a means for shunting said electrical signal when said liquid is in close proximity to at least one of said electrodes of said cluster.
Means for measuring the level of a liquid which include a container wherein the level of a liquid may be measured, at least two electrodes each of which is situated adjacent to the container, and a means electrically coupled to at least one of the electrodes for supplying an electrical signal thereto, have generally been classified as capacitive means and as such are generally known in the art e.g. Radin U.S. Pat. No. 3,641,544 issued Feb. 8, 1972 and Cohen U.S. Pat. No. 2,433,599 issued Dec. 30, 1947. However, previous capacitive means have utilized the liquid to transmit an electrical signal between two electrodes when the liquid is in close proximity to the electrodes thereby completing an electrical circuit. Accordingly, in previous capacitive means the completion of the electrical circuit was necessary in order to detect the desired level of the liquid. As a result of this feature the absence of an electrical signal due to the failure of electronics or any other parts of the capacitive means resulted in a complete failure of the capacitive means itself. Therefore, there were no built-in fail safe provisions in previous capacitive means. Furthermore, since previous capacitive means were dependent upon the transmission of an electrical signal by the liquid it was necessary that the liquid be isolated from ground potential; otherwise, the signal would be shunted thereby preventing it from reaching the receiver electrode and eliminating the detection of the signals presence.